Classifications

• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/04—Oscillators acting by spring tension
  • G04B17/06—Oscillators with hairsprings, e.g. balance
  • G04B17/066—Manufacture of the spiral spring
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F1/00—Springs
  • F16F1/36—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers
  • F16F1/366—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers made of fibre-reinforced plastics, i.e. characterised by their special construction from such materials
  • F16F1/3665—Wound springs
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/20—Compensation of mechanisms for stabilising frequency
  • G04B17/22—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature
  • G04B17/227—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature composition and manufacture of the material used

Definitions

• the present invention generally relates to a mechanical oscillator thermocom thought and i n sensible to u magical cham ps, for watch movement.
• the invention relates to a spiral spring for such a mechanical oscillator, intended to be associated with a balance having a low coefficient of thermal expansion, the spiral spring being made of a first composite material comprising first integrated long fibers in a matrix composed of a thermosetting polymer.
• the invention also relates to a method of manufacturing such a spiral spring, a method of manufacturing a sprung-balance assembly, and a watch movement provided with such a mechanical oscillator and a timepiece featuring such a watch movement.
• patent application EP 2407831 A1 mentions the production of a spiral spring made of silicon, diamond, or even quartz, in an attempt to address the above problem.
• the inventor proposes to complete the teaching of this PCT application with that of the subsequent British patent, in which he describes how to make a balance whose behavior, as a function of temperature, is complementary to that of the spiral spring previously described.
• the balance comprises arms carrying a serge, these elements being made of respective materials having opposite behavior as a function of temperature, so that the moment of inertia of the pendulum varies little with the temperature. Indeed, the deformations of the arms, on the one hand, and the serge, on the other hand, compensate each other.
• T is the period of the oscillations
• J is the moment of inertia of the balance
• G is the pair of the spiral spring.
• the pair of the spiral is given by:
• E is the Young's modulus of the spiral spring
• L is the length of the spiral spring
• I is the quadratic moment of the cross-section of the spiral spring.
• the inventor of the two inventions of the prior art presented above has therefore proposed to fulfill this condition by minimizing, on the one hand, the two terms relating to the properties of the spiral spring and, on the other hand, the relative term. to the properties of the pendulum, so that the residual values of the one and the other part eventually compensate each other.
• a main object of the present invention is to propose a more precise and more flexible approach to the problem to be considered for optimize the choice of materials that can be used to realize a mechanical oscillator, insensitive to external magnetic fields and temperature variations.
• Another object of the present invention is to provide a simple manufacturing method of the spiral spring, or even the complete balance-spiral assembly.
• the Applicant has done research to take into account the anisotropic properties of certain nonmagnetic materials suitable for use in making a sprung balance. This research has made it possible to define materials that make it possible to obtain optimal behavior of the sprung balance when it undergoes temperature variations.
• the present invention relates more particularly to a spiral spring as mentioned above, characterized in that the first long fibers comprise a preponderant part of silica and that the composite material used for producing the spiral spring comprises in in addition to at least second long fibers taken from the group comprising carbon fibers and aramid fibers, the second long fibers also being integrated into the matrix.
• long fibers comprising a preponderant part of silica, on the one hand, and carbon or aramid fibers, on the other hand, have com porteme nts o pposés in response to the va of the surrounding temperature.
• the combination of such materials within the matrix, to achieve the spiral spring can limit the impact of changes in the surrounding temperature on the operation of a sprung balance with such a spiral spring.
• the first and second long fibers are substantially oriented in the longitudinal direction of the spiral spring, preferably being substantially parallel to each other.
• the first and second long fibers advantageously have respective diameters of less than 15 ⁇ m, preferably less than 12 ⁇ m.
• the matrix represents a volume proportion substantially between 20% and 40%, preferably between 25% and 35%, of the entire spiral spring.
• the matrix may advantageously comprise an Epoxy type polymer.
• the second long fibers comprise fibers from the group comprising T700SC type carbon fibers, M40J type carbon fibers, and Kevlar®49 type aramid fibers.
• the first long fibers to comprise quartz fibers, basalt fibers and / or glass fibers taken from the group consisting of type S glass fibers, type E, or type H.
• the present invention also relates to a mechanical oscillator comprising a spiral spring meeting the characteristics which have just been exposed and associated with a rocker made of a material having a coefficient of thermal expansion substantially less than 20.10-6 K- 1 .
• the balance is advantageously made of a second composite material comprising carbon fibers embedded in a matrix preferably composed of a thermosetting polymer.
• the balance comprises a central axis which extend at least two arms integral with a serge. It is preferably provided that the arms and the serge are made in one piece and that the serge further comprises metal charges of at least one non-magnetic type metal. It is also possible that the spiral spring and the balance are made in one piece.
• the present invention also relates to a watch movement and a timepiece comprising a mechanical oscillator meeting the above characteristics.
• the present invention also relates to a method of manufacturing a spiral spring meeting the characteristics which have just been exposed, the method comprising the steps of:
• first parallelepiped-shaped band and made of a prepreg material comprising a matrix composed of a thermosetting polymer containing first long fibers, having a preponderant part of silica, and at least second long fibers taken from the group consisting of carbon fibers and aramid fibers;
• the step of heating the hairspring is performed with application of a pressure on the hairspring to form a spiral plane spring.
• the balance can be made in one piece with the spiral spring.
• the above method comprises additional steps of:
• the second strip comprising at least first and second layers of a composite material comprising a matrix, composed of a thermosetting polymer, and containing carbon fibers, the carbon fibers of one of the layers having an orientation of + 45 ° with reference to the direction of the first band, while the carbon fibers of the other layer have an orientation of -45 ° with reference to the direction of the first band;
• Figures 1a and 1b are graphs illustrating properties of certain materials relevant for the implementation of the present invention.
• FIG. 1 is a graph illustrating an additional property of an exemplary material adapted to the implementation of the present invention.
• FIG. 3 is a schematic view illustrating a first step of implementing a method of manufacturing a sprung balance assembly according to a preferred embodiment of the present invention
• FIG. 4 is a schematic view illustrating a second step of implementing a method of manufacturing a sprung balance assembly according to a preferred embodiment of the present invention
• FIG. 5 is a schematic view illustrating a third step of implementing a method of manufacturing a balance-hairspring assembly according to a preferred embodiment of the present invention
• FIG. 6 is a schematic view illustrating a fourth step of implementing a method of manufacturing a balance-hairspring assembly according to a preferred embodiment of the present invention
• FIG. 7 is a diagrammatic view illustrating a fifth step of implementing a method for manufacturing a balance-hairspring assembly according to a preferred embodiment of the present invention.
• FIG. 8 is a simplified perspective view illustrating a sprung balance assembly obtained by the implementation of the method illustrated in Figures 3 to 7. Mode (s) of realization of the invention
• Each of the phases, fibers or matrix has its own rigidity and its own coefficients of thermal expansion, the fibers themselves being anisotropic.
• these materials comprise first long fibers comprising a preponderant part of silica (that is to say at least 50% silica), preferably glass fibers, basalt fibers and / or quartz fibers, which are associated with at least second long fibers selected from the group consisting of carbon fibers and aramid fibers.
• the carbon fibers may be chosen from the group comprising T700SC type fibers and M40J type fibers or the like (such fibers are marketed by Torayca, see http://www.torayca.com) .
• the glass fibers may be selected from the group consisting of type S glass fibers, type E glass fibers and type H glass fibers or the like (such fibers are sold by Owens Corning Company).
• the quartz fibers may for example comprise Quartzel® fibers (sold by the company Saint-Gobain, see http://www.quartz.saintgobain.com), and the fibers sold by the company Basaltex may be used for basalt fibers (see http://www.basaltex.com).
• Quartzel® fibers sold by the company Saint-Gobain, see http://www.quartz.saintgobain.com
• Basaltex may be used for basalt fibers (see http://www.basaltex.com).
• Kevlar®49 this material being marketed by DuPont, see http://www.dupont.com).
• the fibers preferably have a length corresponding substantially to the length of the spiral spring and are preferably oriented in the longitudinal direction of the latter, being substantially parallel to each other.
• the Applicant has found that the retained fibers should preferably have a diameter less than 15 ⁇ , even more preferably less than 12 ⁇ , to optimize the homogeneity of the composite material at the scale of the spiral spring.
• Figures 1a, 1b and 2 illustrate a preferred example of implementation of the present invention.
• FIG. 1a shows the variation of the natural frequency of a vibrating beam as a function of temperature, the beam being produced in a composite material comprising an epoxy matrix and S-type glass fibers
• Figure 1b shows the variation of the natural frequency of a vibrating beam as a function of temperature, the beam being made of a composite material comprising an epoxy matrix and T700SC type carbon fibers.
• the Applicant has assessed the relevance to achieve a beam that contains both carbon fibers and glass fibers, embedded in the same matrix composed of polymer. She was able to verify that it is possible to realize a beam whose natural frequency does not evolve according to the temperature.
• a preferred non-limiting embodiment consists in using mainly long carbon fibers and an epoxy resin for its composition, the resin may advantageously be loaded with heavy particles of metal type (in particular platinum or iridium for example).
• metal type in particular platinum or iridium for example.
• Figures 3 to 8 illustrate a method of manufacturing a sprung balance assembly according to a preferred embodiment of the present invention.
• the preferred embodiment of the present invention consists in preparing a prepreg material comprising a first band 1 made of a mixture of at least two fibers. (Carbon and / or aramid, on the one hand, and glass, quartz and / or basalt, on the other hand) and a resin.
• This first band 1 advantageously has a thickness substantially between 30 and 150 ⁇ and a width substantially between 0.2 and 2mm, or even between 0.5 and 2mm, when it comes to producing a mechanical oscillator for a watch.
• the first band 1 is intended to form the spiral spring.
• a second band 2, link is provided. This is preferably composed of two layers of composite materials based on carbon fibers and Epoxy resin, one of which is oriented at -45 degrees and the other at +45 degrees, with reference to the longitudinal direction of the second band.
• a third band 4 is provided for the realization of the pendulum.
• This is preferably made of a prepreg material, comprising long carbon fibers, and an epoxy resin.
• the thickness of the third band 4 increases after a first portion 6, of constant thickness, towards its second end 8.
• the increase in thickness can be obtained by adding prepreg folds as well as by adding metal charges. These latter advantageously have a mean diameter of the order of a few micrometers to be properly trapped in the polymer matrix.
• the first and third strips 1, 4 are arranged flat in parallel directions, the second strip 2 being secured to the first strip 1 by a first end 10 and the third band 4 at its second end 12.
• the second band is oriented in a direction perpendicular to the first and third bands.
• the second band is intended to ensure the transmission of torsional forces between the spiral spring and the balance.
• the balance spring is shaped, as shown in Figure 4.
• the spiral is in the form of a half-ellipse of major axis 2Ri and small axis 2R2, where Ri corresponds to the radius of the largest spiral spring turn that will be obtained and R2 is at least equal the number of turns of the spiral spring obtained multiplies the width of the first band 1.
• the ellipsoid 20 is provided with a central opening (not visible) for receiving a locking shaft 22 polygonal section, square here.
• the prepreg is wrapped around the spiral 20 starting with the second band 2, so that the latter makes at least one complete turn around the locking shaft 22 and can not turn afterwards.
• the locking shaft 22 is then housed in the spiral.
• the locking shaft 22 can be extracted from the spiral at the end of manufacture and may possibly be part of the sprung balance assembly as the main axis of rotation.
• the first band 1 is then wound around the periphery of the spiral 20, taking care to apply a slight tension on the first band 1 to prevent slippage and folds.
• molds 30 are used to form the balance, here four in number. Each of these molds has the shape of a negative of the shape that must present a given portion of the balance to obtain.
• the third band 4 is wound around the molds 30 starting from the center and with a first mold corresponding to the form of a quarter of a pendulum, as shown diagrammatically in FIG. 5.
• first arm 32 of the balance and a first thickness of a first quarter of its serge 34 (visible in FIG. 8) are formed.
• FIG. 6 there is shown a positioning of the second mold 30 in front of the first mold 30, by way of non-limiting illustration. Alternatively, it is possible to provide that the second mold 30 is positioned to be adjacent to one or the other of the first two arms 32, without departing from the scope of the present invention.
• the variation in thickness of the third band 4 is advantageously adjusted so that at the end of the winding the balance obtained is balanced, that is to say that its center of gravity is very close or even confused with its geometric center.
• the assembly obtained is placed in an oven, so as to polymerize the matrix of each of the three parts of the sprung balance assembly.
• the polymerization is carried out during a heating step lasting a few hours at a temperature of between 120 ° C. and 180 ° C., depending on the polymer used.
• the person skilled in the art will not encounter any particular difficulty in adapting the duration and temperature of the heating according to his needs, without departing from the scope of the present invention.
• the spiral 20 is removed while the locking shaft 22 and the molds 30 are held in place.
• the spiral spring produced is flexible but not yet flat.

Landscapes

• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Metallurgy (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Springs (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=49484366

Family Applications (1)

Country Status (3)

Cited By (1)

Families Citing this family (1)

Family Cites Families (5)

• 2013
  • 2013-09-17 FR FR1358948A patent/FR3010804B1/fr active Active
• 2014
  • 2014-09-04 EP EP14759187.9A patent/EP3047337B1/de not_active Not-in-force
  • 2014-09-04 WO PCT/EP2014/068864 patent/WO2015039881A2/fr active Application Filing

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events